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Abstract

Different vaccine and adjuvant combinations are known to rapidly induce antigen presenting cell (APC) maturation and pro-inflammatory cytokine and production, which in turn play an important role in the priming of antigen-specific T cells. Measuring cytokine production systemically in the serum fails to detect localized responses in the lymph nodes draining a subcutaneous immunization site. On the other hand, stimulating APC with vaccine formulations in vitro lacks the complexity of the lymph node microenvironment and the presence of other in vivo factors. Here we analyse cytokine production directly in vaccine draining lymph nodes (dLN) extracted early after in vivo vaccination. To do this we perform cytokine multiplex analysis of supernatants from whole dLN cell suspensions following a brief ex vivo incubation.

Materials and Reagents

C57BL/6 mice from Harlan Laboratories (the Netherlands)Note: All mice used in this protocol were between 6 and 12 weeks of age and were sex and age matched for each individual experiment. Three mice were used per group in each experiment.

OVA257-264 and OVA323-339 peptides Note: Peptides were manufactured by the Protein and Peptide Chemistry Facility (PPCF) of the University of Lausanne.

Statistical tests were performed using GraphPad Prism softwareNote: The different groups were compared using One-way ANOVA with the Dunnett multiple comparison test, comparing all groups to the peptide alone group.

Procedure

Experimental protocol

C57BL/6 mice were immunised with 10 μg OVA257-264 and 10 μg OVA323-339 peptides in 100 μl PBS subcutaneously at the base of the tail: Briefly, mice were restrained in a holding tunnel with an opening at the end to access the base of the tail. About half the length of the needle of the tuberculin syringe was inserted into the subcutaneous layer of skin just above and to the side of the tail. The correct depth can be confirmed by visualizing the bevel just below the skin. The vaccine is slowly injected while keeping pressure at the needle entry point. A bubble of liquid should become visible under the skin. The needle should be withdrawn carefully and the exit point massaged slightly with the fingertip to prevent escape of the vaccine.

Peptides were injected alone or in combination with 50 μg of one of the following adjuvants: CpG-ODN (CpG), HMW Poly (I: C), imiquimod, or Quil A.

Either 12 or 24 h later, mice were euthanised by CO2 asphyxiation followed by cervical dislocation, and dLN (both inguinal LN) were excised.

LNs were rapidly transferred to a 24 well plate containing 250 μl of pre-warmed cIMDM + 5% FBS over a small square of 45 μm nylon gauze. A second piece of gauze was placed on top of the LN tissue, which was then dissociated by gently crushing with the rubber end of a 1 ml syringe plunger, while holding the mesh squares in place with forceps.

The cell suspension was then immediately pipetted into a 96 well u-bottom plate for incubation at 37 degrees for 1, 6 or 12 h.

The plate was centrifuged at 300 x g for 1 min before removing 65 μl of supernatant and freezing it at -20 degrees for later analysis. Note: Samples collected from multiple time-points for combined analysis should always be frozen rapidly to preserve the cytokines. However, analysis can be performed immediately if only a single time-point is to be analysed.

Abbreviated protocol previously published in: Perret et al. (2013). This work was supported by grants from the New Zealand Foundation for Research Science and Technology and the Emma Muschamp Foundation (R. Perret) and from the Swiss National Science Foundation (310030-130812 and CRSII3_141879) and the Medic Foundation (P. Romero). Disclosure of Potential Conflicts of Interest: P. Romero is a consultant/advisory board member of Immatics Biotechnologies, DC Prime, Matwin, and Center for Human Immunology, Pasteur Institute (Paris, France). No potential conflicts of interest were disclosed by the other authors.